Development of a risk assessment tool for deep geothermal projects: example of application in the Paris Basin and Upper Rhine graben

This paper presents the development of a tool to perform risk assessment for deep geothermal projects. The tool is aimed at project developers to help them present their project to local authority, decision-makers and financers so they can highlight how they take into account risks and consider mitigation measures to minimize them. The main criteria for this tool are the simplicity of use, the quality of presentation and flexibility. It is based on results from the H2020 GEORISK project that identified risks that apply to geothermal projects and proposed insurance schemes all over Europe. A characteristic of this tool is that it considers all the categories of risks that a project may face, including geological, technical, environmental risks as well as risks related to the social, economic and political contexts. The tool can be customized: selection of risks in a list that can be completed, adaptable rating scheme for risk analysis, possibility to choose the best display for results depending on the user needs. Two case applications are presented, one in the Paris Basin considering a doublet targeting the Upper Trias, a geological layer that presents some technical challenges; and one in the Upper Rhine graben targeting a fault zone, where the risk of induced seismicity must be carefully considered. A posteriori risk assessment highlights the main issues with these types of projects, and the comparison between the two cases emphasizes the flexibility of the tool, as well as, the different ways to present the results depending on the objective of the analyses.